title: Evidence for an essential lysine at the active site of L-histidinol:NAD+ oxidoreductase; a bifunctional dehydrogenase.
abstract: Histidinol dehydrogenase (EC 1.1.1.23) from Salmonella typhimurium is inhibited by formaldehyde and pyridoxal 5-phosphate (pyridoxal-P). epsilon-Pyridoxyl-lysine is isolated upon acid hydrolysis of pyridoxal-P-treated enzyme reduced by sodium borohydride. In the presence of formylhistidinol and formylhistidine (specific ligands of the enzyme) inactivation of histidinol dehydrogenase by pyridoxal-P is prevented. Extrapolation of the initial part of the inactivation curve caused by pyridoxal-P indicates that modification of two essential lysine residues results in inactivation of the dimeric enzyme. The essential lysine residues appear to participate in the reversible oxidation/reduction reaction converting histidinol to histidinal.
mesh_terms: D000429:Alcohol Oxidoreductases / Q000378:metabolism*; D001665:Binding Sites; D005557:Formaldehyde / Q000494:pharmacology; D006641:Histidinol / Q000378:metabolism; D007700:Kinetics; D008239:Lysine; D011485:Protein Binding; D011732:Pyridoxal Phosphate / Q000494:pharmacology; D012486:Salmonella typhimurium / Q000201:enzymology*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D005557:Formaldehyde; D006641:Histidinol; D011732:Pyridoxal Phosphate; D000429:Alcohol Oxidoreductases; C021358:histidinol dehydrogenase; D008239:Lysine